It is frequently desirable to protect an apparatus from unauthorized use or an area from access to all but selected personnel. One way of accomplishing such desiderata is to provide access to an area or use of an apparatus only after a coded switch is properly operated. Such a switch may serve in a capacity similar to that of a combination lock into which the proper code must be inserted before the lock mechanism is released. Many switch designs have been developed and utilized in the past. Most, such as common combination locks, are limited to one code which can not be changed or altered. A number of switches can be recoded, some readily and some only with difficulty. In some situations, a plurality of differently coded switches could be used to control a like plurality of mechanisms, apparatuses or the like. Personnel having knowledge of the code for one such switch need not have knowledge of the code for any other.
It is desirable that the switch provide capability for being checked for proper coding without actually actuating or operating the switch. One known switch capable of performing in such a manner is that taught by U.S. Pat. No. 3,832,873 to Barnette, the inventor herein.